1. Field of the Invention
The invention relates to spun yarn-like textured polyester yarns having broken filaments and high bulkiness and a process for the production thereof in which the broken filaments and high bulkiness are produced by simultaneous draw-texturing of two types of undrawn polyester multifilament yarns of different properties.
2. Description of Prior Art
Attempts have been made to impart effects resembling a spun yarn to a continuous multifilament yarn by producing broken filaments, loops, snarls or the like on the multifilament yarn. However, no satisfactory multifilament yarn having effects closely resembling a yarn obtained by spinning short fibers has hitherto been obtained. Particularly, it is difficult to impart to such a yarn fullness and softness, i.e. an effect such as resulting from the pore produced by the ends of the short fibers incorporated into the yarn by the genuine twist of spinning.
There are two methods for producing broken filaments on a continuous multifilament. One is a method of cutting some of the component filaments by bring the surface of the yarn into contact with a cutting device having a rough surface (see, for example, Japanese Patent Publication No. 48-15693); the other is a method wherein a doubled yarn consisting of a core component and a covering component is brought into contact with a similar cutting device to mainly cut the filaments of the covering component (see, for example, Japanese laid-open Patent Specification No. 49-133643). These methods have, however, a drawback in that it is difficult to control the resulting broken filament count.
As methods utilizing the difference in properties of the material yarns, there are a method wherein a yarn consisting of a multifilament component of a low strength and a multifilament component of an ordinary strength is false twisted and then passed through a stream of a high speed fluid to mainly cut the filaments of the low strength component (see, for example, Japanese laid-open Patent Specification No. 47-30957); a method wherein two mutlifilament undrawn yarns having different limiting draw ratios are doubled and then subjected to simultaneous draw-texturing at a draw ratio such that the filaments of the yarn of a low limiting draw ratio are cut but the filaments of the yarn of high limiting draw ratio are not cut (see, for example, Japanese laid-open Patent Specification No. 49-116351), and; a method wherein a multifilament yarn having, at least partially, a flex abrasion resistance cycle of less than 1,500 is false twisted to produce broken filaments (see, for example, U.S. Pat. No. 3,857,233). These methods have also drawbacks in that it is difficult to control the broken filament count of the resulting yarn, the resulting yarns are inferior in frosting resistance and/or they are inferior in processability due to the frequent occurrence of yarn breakage. Furthermore, the yarns obtained by these methods have insufficient fullness and softness as hereinbefore mentioned.